Field of the Invention
Aspects of the present invention generally relate to a radiation imaging apparatus and a radiation imaging system.
Description of the Related Art
As radiation imaging apparatuses for use in medical diagnostic imaging or nondestructive testing using radiation rays, such as X-rays, there has been put to practical use a radiation imaging apparatus including a matrix substrate having an array of pixels each composed of a combination of a switch, such as a thin-film transistor (TFT), and a conversion element, such as a photoelectric conversion element.
In recent years, radiation imaging apparatuses having multiple functions have been considered. These functions include a built-in function of monitoring irradiation with radiation rays. This function enables, for example, detection of timing at which irradiation with radiation rays from a radiation source has been started, detection of timing at which irradiation with radiation rays is to be stopped, and detection of the dosage or cumulative dosage of radiation rays.
Japanese Patent Application Laid-Open No. 2012-15913 discusses a radiation imaging apparatus in which imaging pixels, which are used to acquire a radiation image, and detection pixels, which are used to detect radiation rays, are arrayed in a matrix shape. The radiation imaging apparatus has also a configuration to read out a signal for detecting radiation rays via a switch connected to each detection pixel. Furthermore, the radiation imaging apparatus discussed in Japanese Patent Application Laid-Open No. 2012-15913 has a configuration in which a plurality of detection pixels is arranged in a particular region in a concentrated manner and a configuration in which switch elements connected to a plurality of detection pixels are concurrently made conductive to read out signals.
However, in the radiation imaging apparatus discussed in Japanese Patent Application Laid-Open No. 2012-15913, at the time of switching of the conductive state, along with a change in voltage of a control line connected to a switch element, a parasitic element (parasitic capacity) occurring between the control line and a signal line may cause a variation in potential of the signal line.
In particular, in a case where signals are concurrently read out from a plurality of detection pixels arranged in a particular region, the influence of a variation in potential of the signal line may become remarkable. Therefore, the accuracy of detection of irradiation with radiation rays may be inadequate.